1 //===- Hello.cpp - Example code from "Writing an LLVM Pass" ---------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements two versions of the LLVM "Hello World" pass described
11 // in docs/WritingAnLLVMPass.html
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/Pass.h"
16 #include "llvm/Function.h"
17 #include <iostream>
18 using namespace llvm;
19 
20 namespace {
21   // Hello - The first implementation, without getAnalysisUsage.
22   struct Hello : public FunctionPass {
23     virtual bool runOnFunction(Function &F) {
24       std::cerr << "Hello: " << F.getName() << "\n";
25       return false;
26     }
27   };
28   RegisterOpt<Hello> X("hello", "Hello World Pass");
29 
30   // Hello2 - The second implementation with getAnalysisUsage implemented.
31   struct Hello2 : public FunctionPass {
32     virtual bool runOnFunction(Function &F) {
33       std::cerr << "Hello: " << F.getName() << "\n";
34       return false;
35     }
36 
37     // We don't modify the program, so we preserve all analyses
38     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
39       AU.setPreservesAll();
40     };
41   };
42   RegisterOpt<Hello2> Y("hello2", "Hello World Pass (with getAnalysisUsage implemented)");
43 }
44